1. Field of the Invention
The present invention relates to wheel assemblies, and more particularly to wheel assemblies for self-loading and unloading transport-type vehicles.
2. Brief Description of the Prior Art
The prior art shows several straddle-type vehicles adapted to move to a position above a load or article, and then to pick up and transport the load within a defined area. Prior art patent references, such as Cellini (U.S. Pat. No. 3,315,829), to be discussed fully later, show a self-loading and unloading transport vehicle. The prior art discloses a transport vehicle that straddles an article, and then picks up that article from beneath the article. The prior art has long used permanent overhead or raised transverse structures relative to the load or article to provide lateral structural support. The transverse structure is positioned above the article and main longitudinal structure of the vehicle itself, and supports the article or load from that superimposed position. Movable transverse structures are known, but only from the overhead or superimposed position.
No transverse structure lies generally in the plane of the main longitudinal structure. Such an arrangement permits construction of a vehicle that can travel outside a defined area on public roads. The prior art is devoid of self-loading and unloading transport vehicles that are capable of travel over relatively large distances on government-owned and maintained highways. There are specially adapted commercially available conventional flatbed trailers that utilize hydraulic hoists or lifting mechanisms to raise a load to a position wherein the load can be placed on the flatbed. Such systems have drawbacks related generally to the fact that the hydraulic hoist or lifting mechanism is purely an add-on feature. Specific drawbacks arise because the lifting mechanism is usually of limited size and requires several lifts to load even a relatively small truck bed at a single location.
Nowhere in the prior art patents found is a true over-the-road self-loading and unloading transport vehicle found. In order to accomplish this over-the-road feature, a unique trailer frame box support structure is provided. The wheel of the present invention incorporated into the frame is relatively easily and quickly removed for tire change resulting from repair, wear or the like. In virtually all loading and unloading transport vehicles, considerable compromise must be made to the supporting wheel structure. This normally results in a cumbersome wheel mounting arrangement that is unsuited to over-the-road travel. Because the prior art is not capable of highway travel, no suspension for a self-loading and unloading trailer is shown. A wheel assembly for a motor cycle having a three piece hub is shown in D. Hicks (U.S. Pat. No. 1,269,437).
Over-the-road trailer vehicles conventionally require eight tandemly-mounted wheels and tires mounted upon the rims thereof. The eight tires are, therefore, conventionally mounted in four groups of two adjacent tires. Governmental restrictions currently require that trailers not exceed a width of eight feet, which means that, if an over-the-road trailer is to maintain the legal eight foot bed width dimension, a straddle-type configuration will mean that very little room between wheels is available in which to fit a load when the wheels are spaced two abreast.
Longitudinally aligning four wheels along each side of a trailer vehicle to allow for straddle-type loading and unloading and to compensate for this deficiency has not heretofore been shown in a self-loading and unloading trailer. Longitudinally aligned wheels enclosed within a frame must be changed periodically. No changeable wheel is shown in the prior art.
Straddle-type transport vehicles are seen at least as far back as U.S. Pat. No. 2,333,208 to Spear. Spear is not an over-the-road vehicle, but rather a carrier used for conveying and laying bulky drain pipes. It therefore includes a pair of longitudinally extending parallel slide rods connecting the transverse structural support members so prevalent in the prior art, which members in turn connect to and are supported by a pair of curved legs. The entire structure has a movable carriage adaptable to move along the slide rods and provide independent movement of the supported drain pipe vis-a-vis the carrier itself.
A tubular frame for releasably locking missile handling devices thereto is shown in Gilbert (U.S. Pat. No. 3,170,582). Again, a transverse structure is superimposed over the load to be handled during the pick-up and transport operations.
Transport vehicles, in many respects similar to Spear, are seen in Kumferman (U.S. Pat. No. 3,181,717; Cellini (U.S. Pat. No. 3,315,829); Tax (U.S. Pat. No. 3,520,431); Parker (U.S. Pat. No. 4,072,241); and Lenius (U.S. Pat. No. 4,143,781). All of these transport vehicles use leg members mounted to wheels to straddle a load. A transverse structure of some type superimposes the article being handled to permit movement of the vehicle over the load so that pick-up can occur. Kumferman shows the ability to handle oversized vertically-dimensioned objects by pivoting a transverse structural member connecting a pair of legs together vertically and out of the path of the article to be straddled.
Cellini does have provision for self-loading and unloading the transport vehicle. Loading is accomplished by using a pivotal post having a chain operatively connected thereto so that an operator can lift a load and slide a pallet under the load. The load can then be engaged by hydraulically operated side members. Thus, a load can be picked up whether or not it is supported on a pallet or blocks. The side members do have inwardly extending tines which support the load to be lifted. Cellini is limited, as are all other prior art references found, to the handling of a single article at one time.
Several of the straddle-like vehicles have provision for centering the load that is picked up with respect to the lifting carriage portion, as seen in Tax, or over the load-bearing wheels, as is done in Parker. Lenius also centers a straddle-type carrier by using three parallel flexible members passing through a pulley system.